Hoping someone can help...I'm having a hell of a time with my lowrance unit. Bought it last year and it worked fine.This year is having problems reading depths, seems like any muddy bottom screws the sonar up and all i get is flashing on the depth.Any ideas what could be causing this?I thought maybe I was getting interference by another component, i added a radio to the boat and there is a speaker near the front that is close to the unit. However I put a switch on the radio so there should be no noise interference when the switch is turned off.any ideas??